Below are links to some of my favorite music magazines. Many of them have lots of free content on their websites as well.
 

http://www.guitarplayer.com/
My favorite guitar magazines. They cover artists of all styles and have lots of great information every month.

http://www.bassplayer.com/
A great magazine devoted to bass players.

http://www.acousticguitar.com/
A great magazine dedicated to the acoustic guitar.

http://www.downbeat.com
Downbeat magazine is dedicated to all things jazz related.

http://www.rollingstone.com/
Rolling Stone focuses a bit more on popular music of all kinds.

http://www.guitarworld.com/
Magazine focusing more on rock & roll.